Rotors for rotary gas compressors and motors



2, 1955 P. H. N. ULANDER 2,714,314

ROTORS FOR ROTARY GAS COMPRESSORS AND MOTORS Filed May 15, 1951 2 Sheets-Sheet l FIG 2 FIG.

m INVENTOR Per Helge Nutonael Ulonder ATTORNEYS Aug. 2, 1955 P. H. N. ULANDER ROTORS FOR ROTARY GAS COMPRESSORS AND MOTORS 2 Sheets-Sheet 2 Filed May 15, 1951 INVENTOR Per Helge Ncnonuel Ulunder BY fizz M ATT'ORNEYS ROTORS FOR ROTARY GAS COMPRESSORS AND MOTORS Per Helge N. Ulander, London, England, assignor to James Howtlen & Company Limited, Glasgow, Scotland, a corporation of Great Britain and Northern Ireland Application May 15, 1951, Serial No. 226,385

10 Claims. (Cl. 74-434) This invention relates to lobed rotors for rotary gas compressors and motors.

It is customary to manufacture rotors from castings or from solid forgings, the resultant rotors being heavy and having high moments of inertia. In addition, the cost of production is high.

A lobed rotor according to the invention comprises a set of metal pressings constituting lobes welded to a tubular hub, and stub axles welded to the ends of the hub.

A practical embodiment of the invention is illustrated in the accompanying drawings in which Fig. 1 is a pictorial view of a male rotor having helical lobes, before the stub axles are attached, Fig. 2 is a pictorial view of the male rotor of Fig. 1 in course of construction, Fig. 3 is a pictorial view of a female rotor having helical lobes, before the stub axles are attached, Fig. 4 is a cross section of a male rotor, Fig. 5 is a longitudinal section of a male rotor having straight lobes, and Fig. 6 is a half cross section of a male rotor presenting cooling passages.

In the drawings, and referring first to Figs. 1, 2, 4 and 5, 1 denotes a tubular hub, 2 denotes metal pressings forming the lobes of a male rotor, said lobes being formed in several sections welded together longitudinally at 3, and transversely at 4, the lobes being welded to the hub 1 at 5.

6 (Fig. 3) denotes metal pressings forming the lobes of a female rotor, the lobes 6 being formed of several sections welded to one another longitudinally at 7, and transversely at 8. Adjacent lobes 6 are welded to one another along their edges at 9. 10 denotes stub axles welded to the hub 1.

11 (Fig. 6) denotes an internal set of metal pressings welded to the huh I at 12, and leaving a partly annular passage 13 between the two sets of pressings 2 and 11. 14 (Fig. 5) denotes end plugs welded into the ends of the lobes.

Rotors constructed as described are much lighter than rotors produced by forging or by casting, and, since the lobes are preformed, the amount of material to be machined off to present the finished profile is much reduced. An additional advantage is that cooling fluid may be passed through the hollow lobes or through the partly annular passages presented within the lobes.

What is claimed is:

1. In a lobed rotor for compressors and the like, the combination of a tubular metal hub, a plurality of hollow lobes extending helically in relation to the axis of said tubular hub and each consisting of a pair of sheet metal shells each of arcuate form in cross-section, a helical strip of weld metal joining to one another the shells of each pair, and other helical strips of weld metal joining the shells of each pair to said hub.

2. A lobed rotor as claimed in claim 1, in which each hollow lobe is semi-circular in cross-section and the concave face of each lobe faces toward the tubular metal hub.

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3. A lobed rotor as claimed in claim 1, in which the convex faces of the shells of each pair forming a hollow lobe face toward each other and toward the tubular metal hub of the rotor.

4. A lobed rotor as claimed in claim 1, in which each sheet metal shell extends helically in relation to the axis of the tubular hub.

5. A lobed rotor as claimed in claim 1, in which each sheet metal shell extends the length of the tubular metal hub and comprises a plurality of successive sections extending helically in relation to the axis of the tubular hub, and a strip of weld metal joining adjacent sections of the shell together.

6. A rotor as claimed in claim 1, including an internal hollow lobe in each of said plurality of hollow lobes and spaced therefrom, each internal hollow lobe extending helically in relation to the axis of said tubular hub and comprising a pair of sheet metal shells each of arcuate form in cross-section, a helical strip of weld metal joining to one another the shells of each pair, and other helical strips of weld metal joining the shells of each pair of internal lobes to said hub, each internal lobe being spaced from the surrounding hollow lobe of the rotor and presenting a passageway between the rotor lobe and the internal lobe, said passageway being open for reception of cooling fluid.

7. A lobed rotor as claimed in claim 1, including end pieces respectively closing the ends of the hollow lobes.

8. In a lobed rotor for compressors and the like, the combination of a tubular metal hub, a plurality of hollow lobes of semi-circular cross-section extending helically in relation to the axis of said tubular hub and each consisting of a pair of metallic shells, a helical strip of weld metal joining to one another the shells of each pair, and other helical strips of weld metal joining the shells of each pair to said hub.

9. In a lobed rotor for compressors and the like, the combination of a tubular metal hub, a plurality of hollow lobes extending helically in relation to the axis of said tubular hub and each including a pair of similar sheet metal shells each of arcuate form in cross-section extending the length of the hub, an edge of one shell of each pair being located adjacent an edge of the other shell of that pair, a helical strip of weld metal joining to one another the said adjacent edges of the shells of each pair, and other helical strips of weld metal joining the shells to said hub.

10. In a compressor including a male rotor and a female rotor, each rotor comprising a tubular metal hub and a plurality of hollow lobes extending helically in relation to the axis of the tubular metal hub and each including a pair of sheet metal shells each of arcuate form in cross-section, a helical strip of weld metal joining to one another the shells of each pair, other helical strips of weld metal joining the shells of each pair to the hub with which they are associated, the lobes of the male rotor being semi-circular in cross-section and having their concave faces directed toward the tubular hub, the convex-shaped faces of the pair of shells forming each lobe of the female rotor being directed toward each other and toward the tubular hub of the female rotor.

References Cited in the file of this patent UNITED STATES PATENTS Re. 21,374 Moineau Feb. 27, 1940 103,733 Gilchrist May 31, 1870 736,039 Wainwright Aug. 11, 1903 2,325,617 Lysholm et al. Aug. 3, 1943 2,464,011 Wade Mar. 8, 1949 2,564,093 Bijl Aug. 14, 1951 2,572,334 Guibert Oct. 23, 1951 

